// Package api implements HTTP middleware for the dashboard.
package api

import (
	"fmt"
	"net/http"
	"runtime"
	"time"

	"git.ardenone.com/jedarden/zai-proxy/dashboard/logger"
)

// Middleware is a function that wraps an http.Handler.
type Middleware func(http.Handler) http.Handler

// Chain applies multiple middleware in order.
func Chain(handler http.Handler, middlewares ...Middleware) http.Handler {
	for i := len(middlewares) - 1; i >= 0; i-- {
		handler = middlewares[i](handler)
	}
	return handler
}

// LoggingMiddleware logs all requests with structured JSON logging.
func LoggingMiddleware(next http.Handler) http.Handler {
	log := logger.Component("http")

	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		start := time.Now()

		// Create response wrapper to capture status code
		rw := &responseWriter{ResponseWriter: w, status: http.StatusOK}

		// Process request
		next.ServeHTTP(rw, r)

		// Calculate duration
		duration := time.Since(start)

		// Log the request
		log.Info("request",
			"method", r.Method,
			"path", r.URL.Path,
			"status", rw.status,
			"duration_ms", duration.Milliseconds(),
			"remote_addr", r.RemoteAddr,
			"user_agent", r.UserAgent(),
			"content_length", r.ContentLength,
		)
	})
}

// RecoveryMiddleware recovers from panics and logs them.
func RecoveryMiddleware(next http.Handler) http.Handler {
	log := logger.Component("http")

	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		defer func() {
			if err := recover(); err != nil {
				// Get stack trace
				buf := make([]byte, 4096)
				n := runtime.Stack(buf, false)
				stackTrace := string(buf[:n])

				log.Error("panic recovered",
					"error", fmt.Sprintf("%v", err),
					"path", r.URL.Path,
					"method", r.Method,
					"stack", stackTrace,
				)

				http.Error(w, "Internal Server Error", http.StatusInternalServerError)
			}
		}()

		next.ServeHTTP(w, r)
	})
}

// CORSMiddleware adds CORS headers to responses.
func CORSMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// Set CORS headers
		w.Header().Set("Access-Control-Allow-Origin", "*")
		w.Header().Set("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS")
		w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Authorization")

		// Handle preflight request
		if r.Method == http.MethodOptions {
			w.WriteHeader(http.StatusNoContent)
			return
		}

		next.ServeHTTP(w, r)
	})
}

// responseWriter wraps http.ResponseWriter to capture status code.
type responseWriter struct {
	http.ResponseWriter
	status int
}

func (rw *responseWriter) WriteHeader(statusCode int) {
	rw.status = statusCode
	rw.ResponseWriter.WriteHeader(statusCode)
}

// Flush implements http.Flusher, required for SSE streaming.
func (rw *responseWriter) Flush() {
	if f, ok := rw.ResponseWriter.(http.Flusher); ok {
		f.Flush()
	}
}